docs: def get_form_kwargs(self):
          kwargs = super().get_form_kwargs()
          """
          When the form is posted, don't pass an instance to the form. It should
          create a new one out of the posted data. We also need to nullify any
          IDs posted for inline menu items, so that new instances of those are
          created too.
          """
          if self.request.method == 'POST':
              data = copy(self.request.POST)
              i = 0
              while(data.get('%s-%s-id' % (
                  settings.FLAT_MENU_ITEMS_RELATED_NAME, i
              ))):
                  data['%s-%s-id' % (
                      settings.FLAT_MENU_ITEMS_RELATED_NAME, i
                  )] = None
                  i += 1
              kwargs.update({
                  'data': data,
                  'instance': self.model()
              })
          return kwargs